Decreased levels of circulating regulatory NK cells in patients with head and neck cancer throughout all tumor stages.

BACKGROUND Natural killer (NK) cells play a crucial role in innate immunity as effectors against tumor cells and pathogen-infected cells. Human NK cells can be subdivided into two functional subsets, the immunoregulatory CD56(bright) NK cells and the cytotoxic CD56(dim) NK cells. NK-mediated host defence against tumor cells is strongly impaired in patients with head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS NK cells were isolated from peripheral blood of 70 HNSCC patients and 22 healthy donors by magnetic bead separation and subsequently analyzed using flow cytometric as well as immunohistochemical methods. RESULTS In this work we demonstrate that the population of circulating immunoregulatory CD56(bright) NK cells is lower in the peripheral blood of patients with HNSCC as compared with that in healthy donors, regardless of the individual tumor stage or tumor type. CONCLUSION These data underline the complex network of HNSCC-mediated immunomodulation as part of the immune escape mechanisms of malignant head and neck tumors.